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SQL Anywhere 10.0.1 » MobiLink - Server Administration » Synchronization Techniques » Maintaining unique primary keys » Using global autoincrement

Using global autoincrement Next Page

Declaring default global autoincrement


You can set default values in your database by selecting the column properties in Sybase Central, or by including the DEFAULT GLOBAL AUTOINCREMENT phrase in a CREATE TABLE or ALTER TABLE statement.

Optionally, the partition size can be specified in parentheses immediately following the AUTOINCREMENT keyword. The partition size may be any positive integer, although the partition size is generally chosen so that the supply of numbers within any one partition will rarely, if ever, be exhausted.

For columns of type INT or UNSIGNED INT, the default partition size is 216 = 65536; for columns of other types the default partition size is 232 = 4294967296. Since these defaults may be inappropriate, especially if our column is not of type INT or BIGINT, it is best to specify the partition size explicitly.

For example, the following SQL statement creates a simple table with two columns: an integer that holds a customer identification number and a character string that holds the customer's name. The partition size is set to 5000.

CREATE TABLE customer (
 id   INT          DEFAULT GLOBAL AUTOINCREMENT (5000),
 name VARCHAR(128) NOT NULL,
 PRIMARY KEY (id)
)
See also